Method of mixing fertilizers



Dec. 17, 1929. R 1,739,732

METHOD OF MIXING FERTILIZERS Filed Nov. 10, 1926 wveni'ov $5M, %Z:%m vkI I fltboznug Patented Dec. 17, 1929 UNITED STA JEFFERSON M. IPARBISH, FRICHMOND, VIRGINIA.

METHOD OF MIXING- FERTILIZERS Application filed November 10, 1926.Serial No. 147,578.

This invention relates to a method of and apparatus for mixingpulverized or powdered materials and particularly relates to the mixingof commercial fertilizers.

- In the manufacture of commercial fertilizers itis usual to preparelarge quantities of the several ingredient materials and to store themin a pulverized condition in bins or. warehouses. The mixing of thesematerials preparatory to shipment in their salable form does not alwaysoccur immediately but most usually at a later date. Great care is takenduring this time in the storage of the various materials to guardagainst the formation of lumps therein, but with all the care whichmaybe taken some lumping always. occurs, due to inherent qualities of someof the materials coupled with conditions that cannot easily oreconomically be avoided. .F or 6X ample, the materials known as acidphosphate and nitrate of-soda readily form into lumps in the presence ofeven a small amount of moisture. It is customary, therefore; in theprocess of mixing fertilizers to include a 5 screening 1 operation, andsometimes also a crushing operation for the purpose of removing thelumps so that a homogeneous mixture of pulverized or fine materials maybe obtained. p

The me'thodshere'toforepracticed, so fan as applicant is aware, haveconsisted in forming a batchof measured quantities of theseveralmaterials, raising it by a bucket or'other hoist to an elevated bin,feeding from the bin i to a screen, discarding or recrushin'gthetailings from the screen and finally mixing the fines which passed thescreen into' salable form. The final mixture was put into cars,

' bags or other containers as it camefrom the mixer, or was again takenup in elevators for this purpose. I

1 In the one case, where the taihngs from Y the screen were discarded,it was naturally impossible to obtain a proper mixture from p theweighed materials." In the other case,

where the tailings. from the'screen were returned to the batch, it wasdiflicult to obtain proper'crushing for the-reason thatthe screentailings contained lumps of widely varying 0 sizes; This presenteddifficulties. A crushsary Weight for crushing the big lumps.

These large balls would obviously fail to touch moretha-n a few of thesmaller lumps and hence while well suited for rapid crushing of largerlumps would require a great deal of time for crushing all of the smallerlumps. Again, when small lumps are to be crushed smaller balls would beused and these 7 small balls would be too light to crush large lumps,which. would have to be discarded,

thereby producing an improper mixture'as in the first case where nocrusher at all was used, though of course with a smaller degree oferror.

Where the roller type of crusher is used" and only a single crusheremployed for both fine and-coarse tailings, it must necessarily be setclose to crush the mater" l sufficiently fine. WVhen large lumps of amaterial such as acid phosphate are passed through a small openingbetween rollers, they are highly compressed and instead ofdisintegrating into small particles they tend to become moist and forminto fiat sticky cakes which not only gum the crusher rollers but clogthe openings of the screen.

According to the; present invention, these and many other difficultiesare overcome by a process which includes more than one screening orseparating operation and a corresponding number" of crushing operationsand in which the crusher for each screen is peculiarly adapted to handlethe material refused by its associated screen. By this process all ,ofthe lumps can be broken so that it Will not be necessary, within thelimits of time required for economical mixing, to discard any ofthelumps, wherefore, it will be seen that a. thoroughly accurate mixturewill be produced.

Apparatus for effecting the above mentioned and other beneficial resultsand in which certain features of novelty will be found, is disclosed inthe accompanying drawings, in which:

Fig. 1 is a diagrammatic view principally in front elevation of oneembodiment of apparatus for efiecting this invention; and

Fig. 2 is a similar view of the apparatus as seen from the right ofFig. 1. 7

Referring to the drawings, in which like reference characters refer tolike parts throughout the several views, the numeral 10 designates aconveyor or elevator which may be of the bucket type having buckets 11carried by a chain 12 passing about drive pulleys in the usual way. Theshaft 13 and sprocket drive wheel 14 for the upper pulley appear in thedrawings while the showingof the pulley at the lower end of the elevatoris omitted.

The ingredients to be mixed may be weighed according to the'typeofifertilizer to be prepared and deposited at the lower end of theconveyor accessible to thebuckets. If

desired, a hopper 10 may be employed for this purpose together with abreaker for crushing lumps which are too large to be handled by thebuckets of the conveyor.

A chute 15 leads the material from the top of the conveyor to a primaryseparator or coarse screen 16 provided with a housing 17 drive shaft 18,and pulley 19. The fines from this screen pass into a hopper 20 whilethe tailings enter a chute 21. The tailings from the chute 21 enter acoarse crusher 22, from whence they emerge, after 1 being crushed, intoachute 23 leading into the side of. the elevator 10. The coarse crusher22 may be driven through a shaft 24 and pulley 25; I

The fines which passed through the apertures of the screen 16 anddropped-into hop per 20, flow by way of a chute 26 leading from thehopper into a secondary separator or very fine screen 27. As in the caseof screen 16, the screen 27 is enclosed in a housing 28 and is providedwith a shaft 29 and pulley 30. The fines from thescreen 27 fall into ahopper 31 while the tailings enter a chute 32.

' The tailings'from the chute 32 enter a fine crusher or pulverizer 33,from whence they emerge, after being crushed, into a chute 34 leadinginto the side of the elevator 10. The fines which passed through theaper tures of the screen 27 and dropped into hopper 31, flow from thelower end of the hop per into a feed hopper 35 of a mixer 36. The

mixer is preferably large enough to receive.

an entire batch of mixture but the hopper 31 may be made large enough tohold a part or all of the batch and by providing the lower end of chute31 with a gate the o the batch.

as desired. This mixer may be supported on trunnions and be driventhrough gears 37, 38, a shaft39 and a pulley 40. The mixer dischargesits product by a spout 41 into a sacking hopper 42. r

In operation, a batch of fertilizer, composed of weighted amounts of theseveral ingredients is fed to the buckets at the lower end of theelevator. This unmixed and partiallylumpy batch is raised by theelevator and fed into the coarse screen 16 by way of chute 15. Thescreen 16 removes the large lumps as tailings which are fed into thecoarse crusher 22 by chute 21. The crusher breaks the large lumps intosmaller ones, (no attemptbeingmade to pulverize at this point) and feedsthem back into the batch by way of chute 23. The conveyor takes themagain to screen.16 with the body of The fines from screen 16 pass intohopper 20, chute 26 and then into the fine screen 27. The tailings fromthis screen pass thru chute 32 to the fine-crusher or pulverizer 33. Thepulverized material is fed by chute 34 back into the conveyor where itis elevated and passed to screen 16 as before. The material which wouldnot orginal- 1y pass screen 27 is broken sufficiently by tiecoarse-crusher 22 and pulverizer 33 to cause it to do so when it isreturned thereto, and within a short time the entire batch will havepassed the screen 33 as fines. When the mixer 36 has received the entirebatch from hopper 31 and feed hopper35, it isstarted into operation tostir the several pulverized ingredients into av homogeneous mass. The

spout 41 of the mixer is under the control of an operator and when thebatch has been thoroughly mixed it is passed by spout 41 intothe sackinghopper 42 where it may be sacked, loaded directly into cars, or disposedof in any other desired manner.

graded crushcrs, beneficial results are produced which could not havebeen predicated upona mere duplication of existing apparatus.

While the embodiment illustrated and described is that which is atpresent preferred, it will be understood that various other embodimentsare contemplated as falling within thescope of the appended claim.

Having thus described the invention, what is claimed as new and desiredto be secured by Letters Patent is:

. In a fertilizer mixer, the combination with an elevator and means fordelivering the materials to be mixed to the elevator, of

a coarse screen receiving the materials from the elevator, a coarsecrusher receiving the tailings from the coarse screen and. deliveringthe crushed materials to the elevator, a fine screen receiving the finesfrom the coarse screen, a fine crusher receiving the tailings from thefine screen and delivering the finely crushed materials to the elevator,and a mixer receiving the fines from the fine screen whereby the largeand small lumps in the original mass of materials are separately crushedand. the operation repeated until all of the batch is suitablypulverized and delivered to the mixer.

In testimony whereof I hereunto afiix my signature.

JEFFERSON M. PARRISH.

